1. Field of the Invention
This invention relates generally to a support system for assisting a process diagnosis, and more particularly to a displaying method for performing suitable fault tree display and a process diagnosis support system utilizing the displaying method.
2. Description of the Related Art
Existing power plants, for example, are equipped with a diagnosis support system for assisting an operator to investigate the cause of an abnormal event and to adopt a proper measure.
In this kind of diagnosis support system, an operator investigates the cause of an abnormal event on reference to a fault tree previously created. Specifically, for a fault tree, various possible abnormalities and causes thereof are stored in a memory medium beforehand as one lot of related structural data in such an order as to systematically show their relevant events as well as flows of causal relations; if an abnormality is detected, a fault tree including a portion where the abnormality occurred is retrieved and then is displayed for an operator's review.
The prior technology concerning the construction of this kind of fault tree is exemplified by Japanese Patent Laid-Open Publication 199296/1989.
For an operator to perform monitoring and to adopt a proper measure on a possible abnormality by a fault tree having been created, it preferably is needed to find out a necessary event accurately and quickly and also to recognize the event in greater detail easily. More particularly at the occurrence of an abnormality, a quick and error-free measure is needed and, for this reason, a variety of ideas have hitherto been proposed.
For example, a proposal has been made in which every individual event can be displayed locally on an enlarged scale from a fault tree illustrating the entire construction. According to another proposal, an abnormal course or path is displayed in a different color on a fault tree so that discovery of such an abnormal portion and investigation of a cause of the abnormality can be performed with ease.
This kind of prior art is exemplified by Japanese Patent Laid-Open Publications 121409/1983, 199296/1989, 42535/1990 and 129405/1988. In addition, diagnostic technology utilizing a fault tree is disclosed in, for example, an article "Pump plant failure diagnostic system" in a publication "Technical Journal of Mitsubishi Heavy Industries", Vol. 26, pages 91-95, and Japanese application 102935/1988.